I own a couple of Withings devices (a scale, and a blood pressure monitor) and this doesn’t affect me (for now!) as an existing user, but it still infuriates me. Saving my data in Apple Health is the *primary* reason I bought those devices.

Relatedly, I switched blood glucose monitor brands because my first device (Libre) did not sync to Apple Health: the data was locked in the device app where it was functionally useless to me and my doctor. So I switched to a more expensive brand (Dexcom G7) just so I could keep a complete history in Apple Health. If they ever remove or paywall that integration I will switch again.